This invention relates to improvements in machines for harvesting corn. Mechanical harvesting of corn has taken place for decades. However, efforts continue to improve corn harvesters to make them more efficient and effective because of the unpredictable and usually narrow profit margins involved in farming. As farms have increased in size while the farm work force has diminished, capital investment in equipment has increased in comparison to investment in land and to labor expenses, including returns on the labor of operating individual farmers. Thus there is always a need to further improve the operation and results of the equipment.
A corn harvester generally includes a corn head or front head which removes the ears from the stalks and a separator or thresher which separates the grains of corn from all other materials such as cobs, small pieces of corn husks, tassels, leaves, ear stalks, and broken off pieces of main stalks. Such materials, referred to as trash, are reduced to small pieces and spread more or less uniformly on the field as part of the harvesting operation. It is desirable to reduce the amount of trash to reduce clogging of the aperture slot or various processing mechanisms in the separator.
A corn head in the most modern form includes several corn head assemblies, one for each row which is being harvested in a single pass over the field. As the harvester moves forward the corn plants in each row enter forwardly extending channels leading to the corn head. Generally the corn head includes a stripper plate or snapper plate inclined toward the ground at an angle of about 45.degree.. The plate is provided with a fore and aft extending slot or aperture which is wide enough to receive the lower end of the corn stalk but not wide enough for the stalk and an ear of corn to pass through. As the plate moves forward it exerts a forward and upward force on the ear.
Below the snapping plate in each corn head unit are a pair of snapping rolls the axes of which are inclined toward the ground parallel to the snapper plate aperture and on each side thereof. The rolls rotate in opposite directions to one another engaging the stalk below the snapper plate. The directions of rotation are such as to exert a downward and rearward force on the stalk relative to the snapper plate. The generally opposing forces exerted by the rolls and plate on the stalk and ear snaps off the ear from the stalk. The ears and any trash which do not pass through the aperture are transported to the separator. The stalk generally remains rooted in the ground.
Snapper rolls generally have conical front ends to provide a space for entry of the base of the stalk and cylindrical rear ends which engage the stalk. The front end and the forward portion of the rear end may be provided with helical ridges wound in opposite senses on each roller in a pair to drive the stalk rearwardly relative to the snapper plate. The rear ends of snapper rolls have been provided with circumferentially spaced, axially extending and radially projecting flutes which also engage the stalk. The rolls in each head are registered with one another so that the flutes intermesh in the manner of gears. One version is shown in U.S. Pat. No. 4,233,804.
In the Fischer patent there are snapper rolls which draw the stalk through a stripper plate as previously described. These rolls have conical front ends and cylindrical rear ends. The portions of the rear ends adjacent the front ends are provided with opposite sense helical ridges. The other portions of the bodies are provided with axially extending flutes. In this patent alternate flutes project radially and non-radially from the bodies and cooperate with the other type of flute on the other roll and thereby bend the stalk. All the flutes are tapered from a smaller projection measured radially near the front head to a larger radial projection remote from the head.
In conventional farming the soil is tilled after the crop is harvested in the fall in order to break up the roots and stalks left in the field and again before planting of the next crop to provide loose soil to receive the seed. Low till techniques seek to minimize the number of tillings in order to save on fuel costs for machinery, extend the life of machines or enable larger acreage to be tilled, and save on labor costs or enable the same or larger acreage to be handled by the same or a smaller work force. No till farming takes the ultimate step of eliminating all tillage. Nature is relied upon to decompose the roots and stalks sufficiently to permit planting and growth of the next crop.
Less tillage minimizes soil erosion and pollution of water in wells, aquifers and waterways and minimizes the runoff of plant nutrients, unused commercial fertilizers, and herbicide residues. Less tillage and no till techniques, in particular, are believed to improve moisture retention in the soil aiding future crops because the residue left on the ground with these techniques acts as a mulch. The composting effect of the residue after it has decomposed may in the long-term reduce the need for commercial fertilizer. Low till and no till techniques are encouraged or required on some farmland by laws and regulations concerning pollution and erosion.
Regardless of the techniques used it is desirable for the stalks of corn to be left in the field in a condition which will facilitate rapid decomposition. The need is greatest of course when no till techniques are used.
This invention provides improved snapping action resulting in a cleaner break of the ear from the stalk and less trash running through the separator and also better prepares the stalks for decomposition.